Mbms coexistence in a network with multiple types of base stations

ABSTRACT

A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus may be a femto cell. The apparatus determines MBSFN subframes at a frequency of a first base station. The first base station has a first power class, the apparatus has a second power class lower than the first power class. The apparatus determines, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals by the first base station. The apparatus transmits, at the frequency, unicast control information in a subset of the first set of symbols. The apparatus transmits, at the frequency, unicast data with a reduced power in the second set of symbols.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser. No. 62/008,454, entitled “Improving MBMS Coexistence in a Network with Multiple Types of Base Stations” and filed on Jun. 5, 2014, which is expressly incorporated by reference herein in its entirety.

BACKGROUND

1. Field

The present disclosure relates generally to communication systems, and more particularly, to improving multimedia broadcast multicast service coexistence in a network with multiple types of base stations.

2. Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of a telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The method is one for wireless communication of a user equipment (UE). The method includes communicating with a second base station in a radio resource control (RRC) connected state, receiving a multimedia broadcast multicast service (MBMS) service from a first base station while in an RRC connected state with the second base station. The first base station having a first power class, and the second base station having a second power class lower than the first power class. The method further includes determining that the UE is unable to decode multicast broadcast single frequency network (MBSFN) signals of the MBMS service from the first base station and receiving the MBMS service from the second base station through a unicast channel upon determining that the UE is unable to decode the MBSFN signals of the MBMS service from the first base station. In an aspect, the method further includes maintaining an RRC idle state with the first base station, determining that the UE is in range of the second base station, establishing an RRC connected state with the first base station, and moving in a handoff from the first base station to the second base station upon determining that the UE is in range of the second base station.

The computer-readable medium may be associated with a UE and include code that when executed on at least one processor performs the operations of communicating with a second base station in an RRC connected state, receiving an MBMS service from a first base station while in an RRC connected state with the second base station, in which the first base station has a first power class, and the second base station has a second power class lower than the first power class, determining that the UE is unable to decode MBSFN signals of the MBMS service from the first base station, and receiving the MBMS service from the second base station through a unicast channel upon determining that the UE is unable to decode the MBSFN signals of the MBMS service from the first base station.

In one aspect, the apparatus may include means for communicating with a second base station in an RRC connected state, means for receiving an MBMS service from a first base station while in an RRC connected state with the second base station, the first base station having a first power class, the second base station having a second power class lower than the first power class, means for determining that the UE is unable to decode MBSFN signals of the MBMS service from the first base station, and means for receiving the MBMS service from the second base station through a unicast channel upon determining that the UE is unable to decode the MBSFN signals of the MBMS service from the first base station. The apparatus may further include means for maintaining an RRC idle state with the first base station, means for determining that the UE is in range of the second base station, means for establishing an RRC connected state with the first base station, and means for moving in a handoff from the first base station to the second base station upon determining that the UE is in range of the second base station.

In another aspect, the apparatus may include a memory and at least one processor coupled to the memory, in which the processor is configured to communicate with a second base station in an RRC connected state, receive a MBMS service from a first base station while in an RRC connected state with the second base station, the first base station having a first power class, the second base station having a second power class lower than the first power class, determine that the UE is unable to decode MBSFN signals of the MBMS service from the first base station, and receive the MBMS service from the second base station through a unicast channel upon determining that the UE is unable to decode the MBSFN signals of the MBMS service from the first base station. The at least one processor may be further configured to maintain an RRC idle state with the first base station, determine that the UE is in range of the second base station, establish an RRC connected state with the first base station, and move in a handoff from the first base station to the second base station upon determining that the UE is in range of the second base station.

In another aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The method includes receiving a composite signal comprising an MBSFN signal transmitted by a first base station and a unicast interfering signal transmitted by a second base station, the first base station having a first power class, the second base station having a second power class lower than the first power class, converting the received composite signal to a frequency domain representation, estimating the unicast interfering signal from the frequency domain converted signal, converting the estimated unicast interfering signal into a time domain interfering signal, subtracting the time domain interfering signal from the received composite signal to obtain an interference reduced signal, and decoding the interference reduced signal to recover MBSFN data. In an aspect, the first base station transmits symbols with an extended cyclic prefix, the second base station transmits symbols with a normal cyclic prefix, and the converting the estimated unicast interfering signal includes converting the estimated unicast interfering signal into a set of symbols in the time domain, appending a normal cyclic prefix to each symbol, and appending two or more cyclic prefix appended symbols together to obtain the time domain interfering signal. In another aspect, the first base station transmits symbols with a normal cyclic prefix, the second base station transmits symbols with an extended cyclic prefix, and the converting the estimated unicast interfering signal includes converting the estimated unicast interfering signal into a set of symbols in the time domain, appending an extended cyclic prefix to each symbol, and appending one or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

In one aspect, the apparatus includes means for receiving a composite signal comprising an MBSFN signal from a first base station and a unicast interfering signal from a second base station, the first base station having a first power class, the second base station having a second power class lower than the first power class, means for converting the received composite signal to a frequency domain representation, means for estimating the unicast interfering signal from the frequency domain converted signal, means for converting the estimated unicast interfering signal into a time domain interfering signal, means for subtracting the time domain interfering signal from the received composite signal to obtain an interference reduced signal, and means for decoding the interference reduced signal to recover MBSFN data. In an aspect, the first base station transmits symbols with an extended cyclic prefix, the second base station transmits symbols with a normal cyclic prefix, and the means for converting the estimated unicast interfering signal is configured to convert the estimated unicast interfering signal into a set of symbols in the time domain, append a normal cyclic prefix to each symbol, and append two or more cyclic prefix appended symbols together to obtain the time domain interfering signal. In another aspect, the first base station transmits symbols with a normal cyclic prefix, the second base station transmits symbols with an extended cyclic prefix, and the means for converting the estimated unicast interfering signal is configured to convert the estimated unicast interfering signal into a set of symbols in the time domain, append an extended cyclic prefix to each symbol, and append one or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

In another aspect, the apparatus may include a memory and at least one processor coupled to the memory, and the at least one processor is configured to receive a composite signal comprising an MBSFN signal from a first base station and a unicast interfering signal from a second base station, the first base station having a first power class, the second base station having a second power class lower than the first power class, convert the received composite signal to a frequency domain representation, estimate the unicast interfering signal from the frequency domain converted signal, convert the estimated unicast interfering signal into a time domain interfering signal, subtract the time domain interfering signal from the received composite signal to obtain an interference reduced signal, decode the interference reduced signal to recover MBSFN data. In an aspect, the first base station transmits symbols with an extended cyclic prefix, the second base station transmits symbols with a normal cyclic prefix, and the at least one processor is configured to convert the estimated unicast interfering signal by converting the estimated unicast interfering signal into a set of symbols in the time domain, appending a normal cyclic prefix to each symbol, and appending two or more cyclic prefix appended symbols together to obtain the time domain interfering signal. In another aspect, the first base station transmits symbols with a normal cyclic prefix, the second base station transmits symbols with an extended cyclic prefix, and the at least one processor is configured to convert the estimated unicast interfering signal by converting the estimated unicast interfering signal into a set of symbols in the time domain, appending an extended cyclic prefix to each symbol, and appending one or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

The computer-readable medium includes code that when executed on at least one processor performs the operations of receiving a composite signal comprising n MBSFN signal from a first base station and a unicast interfering signal from a second base station, the first base station having a first power class, the second base station having a second power class lower than the first power class, converting the received composite signal to a frequency domain representation, estimating the unicast interfering signal from the frequency domain converted signal, converting the estimated unicast interfering signal into a time domain interfering signal, subtracting the time domain interfering signal from the received composite signal to obtain an interference reduced signal, and decoding the interference reduced signal to recover MBSFN data.

In another aspect of the disclosure, a method, a computer program product, and an apparatus are provided. The apparatus may be a femto cell, pico cell, relay node, or otherwise a cell/base station with a power class lower than a power class of a macro cell/base station. The apparatus determines MBSFN subframes at a frequency of a first base station (e.g., macro cell or an eNB). The first base station has a first power class, and the apparatus has a second power class. The second power class is lower than the first power class. The apparatus determines, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals by the first base station. The apparatus transmits, at the frequency, unicast control information in a subset of the first set of symbols. The apparatus transmits, at the frequency, unicast data with a reduced power in the second set of symbols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure in LTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure in LTE.

FIG. 5 is a diagram illustrating an example of a radio protocol architecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B and user equipment in an access network.

FIG. 7A is a diagram illustrating an example of an evolved Multimedia Broadcast Multicast Service channel configuration in a Multicast Broadcast Single Frequency Network.

FIG. 7B is a diagram illustrating a format of a Multicast Channel Scheduling Information Media Access Control control element.

FIG. 8 is a diagram illustrating an exemplary method for improving MBMS coexistence in a network with multiple types of base stations by maintaining MBMS service continuity through unicast.

FIG. 9 is a flow chart of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations by maintaining MBMS service continuity through unicast.

FIG. 10 is a diagram illustrating an exemplary method for improving MBMS coexistence in a network with multiple types of base stations via interference cancellation.

FIG. 11 is a flow chart of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations via interference cancellation.

FIG. 12A is a flow chart of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations.

FIG. 12B is a flow chart of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations.

FIG. 13 is a diagram illustrating an exemplary network architecture and method for improving MBMS coexistence in a network with different types of base stations.

FIG. 14A is a diagram illustrating network architecture configured to provide MBMS service.

FIG. 14B is a diagram illustrating an exemplary network architecture and method for improving MBMS coexistence with multiple types of base stations through base station cooperation.

FIG. 15 is a flow chart of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations.

FIG. 16 is a diagram illustrating an exemplary network architecture and method for improving MBMS coexistence with multiple types of base stations through base station cooperation.

FIG. 17 is a flow chart of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations.

FIG. 18 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

FIG. 19 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

FIG. 20 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

FIG. 21 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

FIG. 22 is a conceptual data flow diagram illustrating the data flow between different modules/means/components in an exemplary apparatus.

FIG. 23 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), compact disk ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Combinations of the above should also be included within the scope of computer-readable media.

FIG. 1 is a diagram illustrating an LTE network architecture 100. The LTE network architecture 100 may be referred to as an Evolved Packet System (EPS) 100. The EPS 100 may include one or more user equipment (UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 104, an Evolved Packet Core (EPC) 110, and an Operator's Internet Protocol (IP) Services 122. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108, and may include a Multicast Coordination Entity (MCE) 128. The eNB 106 provides user and control planes protocol terminations toward the UE 102. The eNB 106 may be connected to the other eNBs 108 via a backhaul (e.g., an X2 interface). The MCE 128 allocates time/frequency radio resources for evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS), and determines the radio configuration (e.g., a modulation and coding scheme (MCS)) for the eMBMS. The MCE 128 may be a separate entity or part of the eNB 106. The eNB 106 may also be referred to as a base station, a Node B, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The eNB 106 provides an access point to the EPC 110 for a UE 102. Examples of UEs 102 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, or any other similar functioning device. The UE 102 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

The eNB 106 is connected to the EPC 110. The EPC 110 may include a Mobility Management Entity (MME) 112, a Home Subscriber Server (HSS) 120, other MMEs 114, a Serving Gateway (S-GW) 116, a Multimedia Broadcast Multicast Service (MBMS) Gateway (MBMS-GW) 124, a Broadcast Multicast Service Center (BM-SC) 126, and a Packet Data Network (PDN) Gateway 118. The MME 112 is the control node that processes the signaling between the UE 102 and the EPC 110. Generally, the MME 112 provides bearer and connection management. All user IP packets may be transferred through the Serving Gateway 116, which is connected to the PDN Gateway 118. The PDN Gateway 118 provides UE IP address allocation as well as other functions. The PDN Gateway 118 and the BM-SC 126 are connected to the IP Services 122. The IP Services 122 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a Packed Switched (PS) Streaming Service (PSS), and/or other IP services. The BM-SC 126 may provide functions for MBMS user service provisioning and delivery. The BM-SC 126 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway 124 may be used to distribute MBMS traffic to the eNBs (e.g., 106, 108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

FIG. 2 is a diagram illustrating an example of an access network 200 in an LTE network architecture. In this example, the access network 200 is divided into a number of cellular regions (cells) 202. One or more lower power class eNBs 208 may have cellular regions 210 that overlap with one or more of the cells 202. The lower power class eNB 208 may be a femto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The macro eNBs 204 are each assigned to a respective cell 202 and are configured to provide an access point to the EPC 110 for all the UEs 206 in the cells 202. There is no centralized controller in this example of an access network 200, but a centralized controller may be used in alternative configurations. The eNBs 204 are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway 116. An eNB may support one or multiple (e.g., three) cells (also referred to as a sectors). The term “cell” can refer to the smallest coverage area of an eNB and/or an eNB subsystem serving a particular coverage area depending on the context in which the term is used. Further, the terms “eNB,” “base station,” and “cell” may be used interchangeably herein.

The modulation and multiple access scheme employed by the access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplex (FDD) and time division duplex (TDD). As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the eNBs 204 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data streams may be transmitted to a single UE 206 to increase the data rate or to multiple UEs 206 to increase the overall system capacity. This is achieved by spatially precoding each data stream (i.e., applying a scaling of an amplitude and a phase) and then transmitting each spatially precoded stream through multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UE(s) 206 with different spatial signatures, which enables each of the UE(s) 206 to recover the one or more data streams destined for that UE 206. On the UL, each UE 206 transmits a spatially precoded data stream, which enables the eNB 204 to identify the source of each spatially precoded data stream.

Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread-spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides “orthogonality” that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structure in LTE. A frame (10 ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block. The resource grid is divided into multiple resource elements. In LTE, for a normal cyclic prefix, a resource block contains 12 consecutive subcarriers in the frequency domain and 7 consecutive OFDM symbols in the time domain, for a total of 84 resource elements. For an extended cyclic prefix, a resource block may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive OFDM symbols in the time domain, for a total of 72 resource elements. Some of the resource elements, indicated as R 302, 304, include DL reference signals (DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted only on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structure in LTE. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control section to transmit control information to an eNB. The UE may also be assigned resource blocks 420 a, 420 b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (10 ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer 506. Layer 2 (L2 layer) 508 is above the physical layer 506 and is responsible for the link between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control (MAC) sublayer 510, a radio link control (RLC) sublayer 512, and a packet data convergence protocol (PDCP) 514 sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 508 including a network layer (e.g., IP layer) that is terminated at the PDN gateway 118 on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 512 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 506 and the L2 layer 508 with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516 is responsible for obtaining radio resources (e.g., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650 in an access network. In the DL, upper layer packets from the core network are provided to a controller/processor 675. The controller/processor 675 implements the functionality of the L2 layer. In the DL, the controller/processor 675 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE 650 based on various priority metrics. The controller/processor 675 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 650.

The transmit (TX) processor 616 implements various signal processing functions for the L1 layer (i.e., physical layer). The signal processing functions include coding and interleaving to facilitate forward error correction (FEC) at the UE 650 and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 674 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 650. Each spatial stream may then be provided to a different antenna 620 via a separate transmitter 618TX. Each transmitter 618TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through its respective antenna 652. Each receiver 654RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 656. The RX processor 656 implements various signal processing functions of the L1 layer. The RX processor 656 may perform spatial processing on the information to recover any spatial streams destined for the UE 650. If multiple spatial streams are destined for the UE 650, they may be combined by the RX processor 656 into a single OFDM symbol stream. The RX processor 656 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 610. These soft decisions may be based on channel estimates computed by the channel estimator 658. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB 610 on the physical channel. The data and control signals are then provided to the controller/processor 659.

The controller/processor 659 implements the L2 layer. The controller/processor can be associated with a memory 660 that stores program codes and data. The memory 660 may be referred to as a computer-readable medium. In the UL, the controller/processor 659 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 662, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink 662 for L3 processing. The controller/processor 659 is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets to the controller/processor 659. The data source 667 represents all protocol layers above the L2 layer. Similar to the functionality described in connection with the DL transmission by the eNB 610, the controller/processor 659 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the eNB 610. The controller/processor 659 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a reference signal or feedback transmitted by the eNB 610 may be used by the TX processor 668 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 668 may be provided to different antenna 652 via separate transmitters 654TX. Each transmitter 654TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar to that described in connection with the receiver function at the UE 650. Each receiver 618RX receives a signal through its respective antenna 620. Each receiver 618RX recovers information modulated onto an RF carrier and provides the information to a RX processor 670. The RX processor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. The controller/processor 675 can be associated with a memory 676 that stores program codes and data. The memory 676 may be referred to as a computer-readable medium. In the UL, the controller/processor 675 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 650. Upper layer packets from the controller/processor 675 may be provided to the core network. The controller/processor 675 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

FIG. 7A is a diagram 750 illustrating an example of an evolved MBMS (eMBMS) channel configuration in an MBSFN. The eNBs 752 in cells 752′ may form a first MBSFN area and the eNBs 754 in cells 754′ may form a second MBSFN area. The eNBs 752, 754 may each be associated with other MBSFN areas, for example, up to a total of eight MBSFN areas. A cell within an MBSFN area may be designated a reserved cell. Reserved cells do not provide multicast/broadcast content, but are time-synchronized to the cells 752′, 754′ and may have restricted power on MBSFN resources in order to limit interference to the MBSFN areas. Each eNB in an MBSFN area synchronously transmits the same eMBMS control information and data. Each area may support broadcast, multicast, and unicast services. A unicast service is a service intended for a specific user, e.g., a voice call. A multicast service is a service that may be received by a group of users, e.g., a subscription video service. A broadcast service is a service that may be received by all users, e.g., a news broadcast. Referring to FIG. 7A, the first MBSFN area may support a first eMBMS broadcast service, such as by providing a particular news broadcast to UE 770. The second MBSFN area may support a second eMBMS broadcast service, such as by providing a different news broadcast to UE 760. Each MBSFN area supports a plurality of physical multicast channels (PMCH) (e.g., 15 PMCHs). Each PMCH corresponds to a multicast channel (MCH). Each MCH can multiplex a plurality (e.g., 29) of multicast logical channels. Each MBSFN area may have one multicast control channel (MCCH). As such, one MCH may multiplex one MCCH and a plurality of multicast traffic channels (MTCHs) and the remaining MCHs may multiplex a plurality of MTCHs.

A UE can camp on an LTE cell to discover the availability of eMBMS service access and a corresponding access stratum configuration. In a first operation, the UE may acquire a system information block (SIB) 13 (SIB13). In a second operation, based on the SIB13, the UE may acquire an MBSFN Area Configuration message on an MCCH. In a third operation, based on the MBSFN Area Configuration message, the UE may acquire an MCH scheduling information (MSI) MAC control element. The SIB13 may indicate (1) an MBSFN area identifier of each MBSFN area supported by the cell; (2) information for acquiring the MCCH such as an MCCH repetition period (e.g., 32, 64, . . . , 256 frames), an MCCH offset (e.g., 0, 1, . . . , 10 frames), an MCCH modification period (e.g., 512, 1024 frames), a signaling modulation and coding scheme (MCS), subframe allocation information indicating which subframes of the radio frame as indicated by repetition period and offset can transmit MCCH; and (3) an MCCH change notification configuration. There is one MBSFN Area Configuration message for each MBSFN area. The MBSFN Area Configuration message may indicate (1) a temporary mobile group identity (TMGI), which may identify an MBMS service within a PLMN, and an optional session identifier of each MTCH identified by a logical channel identifier within the PMCH, and (2) allocated resources (i.e., radio frames and subframes) for transmitting each PMCH of the MBSFN area and the allocation period (e.g., 4, 8, . . . , 256 frames) of the allocated resources for all the PMCHs in the area, and (3) an MCH scheduling period (MSP) (e.g., 8, 16, 32, . . . , or 1024 radio frames) over which the MSI MAC control element is transmitted.

FIG. 7B is a diagram 790 illustrating the format of an MSI MAC control element. The MSI MAC control element may be sent once each MSP. The MSI MAC control element may be sent in the first subframe of each scheduling period of the PMCH. The MSI MAC control element can indicate the stop frame and subframe of each MTCH within the PMCH. There may be one MSI per PMCH per MBSFN area.

In networks that support MBMS service through MBSFN transmission, not all types of base stations deployed within such networks may support MBSFN transmission. For example, in an LTE network, eNBs may support MBSFN transmissions, while femto cells, pico cells, and relay nodes may not. The lack of support for MBSFN transmission in femto cells, for example, may be due to issues related to synchronization between a femto cell and an eNB, lack of control of the femto cell by a network operator, the femto cell's lack of MBSFN awareness, femto cell cost and capability, backhaul accessibility, and femto cell configuration.

When certain lower powered base stations like femto cells do not support MBSFN transmissions, such lower powered base stations can cause interference to MBMS service for a UE. Interference can occur when such lower powered base stations transmit unicast signals at the same frequency that MBSFN signals are being transmitted by a higher powered base station. For example, a UE within the coverage area of a femto cell may not efficiently receive MBMS service due to the interference caused by the femto cell to the MBSFN signal being transmitted by an eNB. Interference may be especially severe when the femto cell and the eNB are transmitting on the same frequency. As such, a need exists to improve MBMS coexistence in networks that utilize MBSFN transmission and deploy multiple types of base stations, some of which do not support MBSFN transmissions. Although the examples above have been discussed with respect to a femto cell, the same need applies to other types of base stations, such as relay nodes, which also do not support MBSFN transmissions. Also, the same need applies to pico cells when pico cells do not participate in MBSFN transmissions.

FIG. 8 is a diagram 800 illustrating an exemplary method for improving MBMS coexistence in a network with multiple types of base stations by maintaining MBMS service continuity through unicast. A first base station 802 supports an MBSFN area denoted by cell 804. The first base station 802 has a first power class and may be an eNB. A UE 810 is located within cell 804 and maintains an RRC idle state with the first base station 802. The UE 810 is also within a region 806, which is the coverage area of a second base station 808. The second base station 808 has a second power class in which the second power class may be lower than the first power class. The second base station 808 may be a femto cell. The UE 810 receives signals from both the first base station 802 and the second base station 808. In one configuration, the UE 810 may receive MBSFN signals 812 from the first base station 802 and interfering signals from the second base station 808. If the second base station 808 transmits the interfering signals at the same frequency that the first base station 802 transmits the MBSFN signals 812, the interfering signals may cause severe interference to the UE 810 attempting to receive and decode the MBSFN signals 812 for MBMS service.

The UE 810 may improve the MBMS service, however, if the UE 810 has access to the second base station 808. For example, the UE 810 would have access to the second base station 808 if the identity of the second base station 808 belongs to the Closed Subscriber Group (CSG) whitelist of the UE 810. Because the UE 810 is in region 806, the UE 810 may determine 816 that the UE 810 is in range of the second base station 808. The UE 810 may receive a cell ID from the second base station 808. Based on the cell ID, the UE 810 may determine that the second base station 808 belongs to the UE 810's CSG whitelist. The UE 810 may establish an RRC connected state with the first base station 802. Afterwards, the UE 810 may be handed over from the first base station 802 to the second base station 808, thereby establishing an RRC connected state with the second base station 808, upon determining that the UE 810 is in range of the second base station 808.

In one configuration, the UE 810 may be handed over from the first base station 802 to the second base station 808 if the signal strength (e.g., signal to noise ratio (SNR)) from the second base station 808 exceeds a threshold or is greater than the signal strength from first base station 802. The UE 810 may report the signal strength from the second base station 808 to the first base station 802. The first base station 802 may hand off the UE 810 to the second base station 808 based on the reported signal strength.

After the handoff, the UE 810 may communicate with the second base station 808 in an RRC connected state. During this time, the UE 810 may receive MBMS service from the first base station 802 while being in an RRC connected state with the second base station 808. The MBMS service from the first base station 802 may be transmitted to the UE 810 through MBSFN signals 812. If the MBSFN signals 812 can be decoded, the UE 810 may autonomously release the unicast channel established with the second base station 808 and enter into an RRC idle state with the second base station 808. However, if the UE 810 determines that the UE 810 is unable to decode the MBSFN signals 812 of the MBMS service from the first base station 802, the UE 810 may decide to receive MBMS service from the second base station 808 through unicast signals 814 transmitted by the second base station 808. Thus, by entering an RRC connected state with the second base station 808 while attempting to decode the MBSFN signals 812 from the first base station 802, the UE 810 can choose to receive MBMS service from the second base station 808 with minimal delay if the UE 810 determines that the UE 810 cannot decode the MBSFN signals 812 from the first base station 802.

FIG. 9 is a flow chart 900 of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations by maintaining MBMS service continuity through unicast. The method may be performed by a UE (e.g., the UE 810). At block 902, the UE may be within a cell served by a first base station and may maintain an RRC idle state with a first base station. The first base station may have a first power class. For example, the UE 810 operates in an LTE network and is located within a cell served by the first base station 802. In this example, the UE 810 maintains an RRC idle state with the first base station 802.

At block 904, the UE may determine that the UE is in range of an area served by a second base station. For example, the UE 810 may detect signals from the second base station 808 and determine that the UE 810 is in range of an area served by the second base station 808. The UE 810 may determine that the UE 810 has access to the second base station 808 if the identity of the second base station 808 belongs to the CSG whitelist of the UE 810. For example, the UE 810 may receive a cell ID from the second base station 808, and based on the cell ID, determine that the second base station 808 belongs to the UE's CSG whitelist.

At block 906, the UE may establish an RRC connected state with the first base station. For example, after determining that the UE 810 is in range of the second base station 808, the UE 810 may determine that the second base station 808 is on the UE 810's CSG whitelist based on a received cell ID. The UE 810 may establish an RRC connected state with the first base station 802, knowing that the second base station 808 cannot support MBSFN transmission.

At block 908, the UE may be handed over from the first base station to the second base station upon determining that the UE is in range of the second base station. For example, after the UE 810 determines that the UE 810 is in range of the second base station 808 and that the second base station 808 is on the UE 810's CSG whitelist, the UE 810 may report the received signal strength from the second base station 808 to the first base station 802. The first base station 802 may determine that the signal strength exceeds a threshold (e.g., greater than −70 dBm) and subsequently hand off the UE 810 from the first base station 802 to the second base station 808.

At block 910, the UE may communicate with the second base station in an RRC connected state. For example, after the UE 810 has been handed off from the first base station 802 to the second base station 808, the UE 810 may communicate with the second base station 808 in an RRC connected state.

At block 912, the UE may receive an MBMS service from a first base station while in an RRC connected state with the second base station. For example, the UE 810 may receive MBMS service from the first base station 802 while in an RRC connected state with the second base station 808. If the UE 810 can successfully receive the MBMS service from the first base station 802, the UE 810 may decide to release the unicast channel established with the second base station 808 and enter into an RRC idle state with the second base station 808.

At block 914, however, the UE may determine that the UE is unable to decode the MBSFN signals of the MBMS service from the first base station. For example, the UE 810 may determine that the UE 810 is unable to decode the MBSFN signals 812 of the MBMS service from the first base station 802 because the signal to noise ratio of the received signal from the first base station 802 is too low or because the received signal strength is below a threshold (e.g., <−100 dBm). In another example, the UE 810 may determine that the UE 810 is unable to decode the MBSFN signals 812 of the MBMS service from the first base station 802 because the block error rate is too high.

At block 916, the UE may receive the MBMS service from the second base station through a unicast channel upon determining that the UE is unable to decode the MBSFN signals of the MBMS service from the first base station. For example, the UE 810 may receive the MBMS service from the second base station 808 through the unicast signals 814 upon determining that the UE 810 is unable to decode the MBSFN signals 812 of the MBMS service from the first base station 802.

FIG. 10 is a diagram 1000 illustrating an exemplary method for improving MBMS coexistence in a network with multiple types of base stations via interference cancellation. A first base station 1002 supports an MBSFN area denoted by cell 1004. The first base station 1002 has a first power class and may be an eNB. A UE 1010 is located within the cell 1004 and maintains an RRC idle state with the first base station 1002. The UE 1010 is also within a region 1006, which is the coverage area of a second base station 1008. The second base station 1008 has a second power class, and the second power class may be lower than the first power class. The second base station 1008 may be a femto cell, pico cell, relay node, or other lower power class base station. The UE 1010 receives signals from both the first base station 1002 and the second base station 1008. In one configuration, the UE 1010 may receive a composite signal 1016 that includes an MBSFN signal 1012 from the first base station 1002 and a unicast interfering signal 1014 from the second base station 1008. If the second base station 1008 transmits the unicast interfering signal 1014 at the same frequency that the first base station 1002 transmits the MBSFN signal 1012, the unicast interfering signal 1014 may cause severe interference to the UE 1010 attempting to receive and decode the MBSFN signal 1012 for MBMS service.

If the second base station 1008 is on the CSG whitelist of the UE 1010, the UE 1010 can receive the MBMS service through the second base station 1008 as discussed above. However, the UE 1010 may not have access to the second base station 1008, may not know the type of base station/cell detected, or may not want to prepare for handoff to the second base station 1008. In such cases, the UE 1010 may reduce interference by canceling at least some of the unicast interfering signal 1014 transmitted by the second base station 1008 when decoding the composite signal 1016 that includes the MBSFN signals 1012 transmitted by the first base station 1002.

Different methods may be used by the UE 1010 to cancel interference depending on whether the MBSFN signal 1012 and the unicast interfering signal 1014 have the same or different cyclic prefixes. When the MBSFN signal 1012 and the unicast interfering signal 1014 have the same cyclic prefix (e.g., an extended cyclic prefix), the UE 1010 may cancel the unicast interfering signal 1014 based on channel estimation, traffic to power ratio, rank, precoding, and/or the mean of the modulation symbol of the unicast interfering signal 1014 in the frequency domain. Initially, the UE 1010 may reconstruct the unicast interfering signal 1014 in the frequency domain. Subsequently, the UE 1010 may cancel the unicast interfering signal 1014 in the frequency domain and capture the cancellation noise.

However, if the MBSFN signal 1012 and the unicast interfering signal 1014 have different cyclic prefixes (e.g., the MBSFN signal 1012 has an extended cyclic prefix and the unicast interfering signal 1014 has a normal cyclic prefix), a different method of interference cancellation may be used. In one aspect, when cyclic prefixes are the same, frequency domain cancellation may be used to reduce interference. However, when cyclic prefixes are different, time domain cancellation may be used to reduce interference. In time domain cancellation, subframe or symbol level based cancellation is performed due to the misalignment of the symbol boundaries between unicast and MBSFN transmissions. An appropriate cyclic prefix length is appended to each symbol of the estimated interfering signal before the cancellation.

To illustrate time domain cancellation, referring to FIG. 10, the UE 1010 may receive a composite signal 1016 that includes the MBSFN signal 1012 from the first base station 1002 and the unicast interfering signal 1014 from a second base station 1008. The first base station 1002 may have a first power class, and the second base station 1008 may have a second power class that is lower than the first power class. The received composite signal 1016 may be in the time domain. Upon receiving the composite signal 1016, the UE 1010 may save the composite signal 1016 in a buffer. The UE 101 may perform a series of operations 1018 in an attempt to cancel the unicast interfering signal 1014 from the received composite signal 1016. The UE 1010 may convert the received composite signal 1016 from a time domain representation to a frequency domain representation by using, for example, a Fast Fourier Transform (FFT). The UE 1010 may estimate the unicast interfering signal 1014 from the frequency domain converted signal. In one aspect, the UE 1010 may estimate the unicast interfering signal 1014 by estimating or determining one or more relevant parameters related to unicast signal transmission. For example, the UE 1010 may estimate one or more of a unicast channel, traffic to pilot ratio, rank (i.e., number of layers), precoding matrix, transmission mode, modulation order, modulation symbol, and residual interference. In some instances, one or more of these parameters may be transmitted to the UE 1010 from a wireless network (e.g., via network assistance from the first base station 1002). Based on one or more of these parameters, the UE 1010 may estimate the unicast interfering signal 1014. The UE 1010 may convert the estimated unicast interfering signal from the frequency domain to the time domain using, for example, Inverse Fast Fourier Transform (IFFT), to obtain a time domain estimated unicast interfering signal.

The UE 1010 may convert the estimated unicast interfering signal from the frequency domain to the time domain under two configurations. In one configuration, the first base station 1002 may transmit symbols with an extended cyclic prefix (e.g., an MBSFN subframe with 12 symbols), and the second base station 1008 may transmit symbols with a normal cyclic prefix (e.g., a unicast subframe with 14 symbols). In this configuration, the UE 1010 may convert the estimated unicast interfering signal into a set of symbols in the time domain. Because the unicast interfering signal 1014 has a normal cyclic prefix, the UE 1010 may append a normal cyclic prefix to each symbol in the time domain. To cancel interference from MBSFN signal 1012, which has an extended cyclic prefix, the UE 1010 may need at least two symbols from the estimated unicast interfering signal with appended normal prefixes. Accordingly, the UE 1010 may append two or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

In another configuration, the first base station 1002 may transmit symbols with a normal cyclic prefix (e.g., an MBSFN subframe with 14 symbols), and the second base station 1008 may transmit symbols with an extended cyclic prefix (e.g., a unicast subframe with 12 symbols). In this configuration, the UE 1010 may convert the estimated unicast interfering signal into a set of symbols in the time domain. Because the unicast interfering signal 1014 has an extended cyclic prefix, the UE 1010 may append an extended cyclic prefix to each symbol in the time domain. To cancel interference from MBSFN signal 1012, which has a normal cyclic prefix, the UE 1010 may use one or more symbols from the estimated unicast interfering signal with appended extended prefix. Accordingly, the UE 1010 may append one or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

Having obtained the estimated time domain interfering signal in either of the aforementioned configurations, the UE 1010 may subtract the estimated time domain interfering signal from the received composite signal 1016 to obtain an interference reduced signal. The UE 1010 may then decode the interference reduced signal to recover/obtain MBSFN data/transmission that approximates (or is approximately equal to) the MBSFN signal 1012 transmitted by the first base station 1002.

As previously mentioned, in an aspect, instead of performing symbol level based cancellation, the UE 1010 may perform subframe level based cancellation (excluding unicast control symbols) due to misaligned symbol boundaries between unicast and MBSFN signals when the cyclic prefix length is different.

Further, by improving MBMS coexistence using interference cancellation, no coordination is needed between the second base station 1008 and/or other lower powered base stations) and the first base station 1002. The second base station 1008 also need not be aware of the MBSFN subframes being transmitted by the first base station 1002.

FIG. 11 is a flow chart 1100 of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations via interference cancellation. The method may be performed by a UE (e.g., the UE 1010). At block 1102, the UE may receive a composite signal that includes an MBSFN signal from a first base station and a unicast interfering signal from a second base station. The first base station may have a first power class. The second base station may have a second power class. The second power class may be lower than the first power class. For example, referring to FIG. 10, the UE 1010 may receive a composite signal 1016 that includes an MBSFN signal 1012 from a first base station 1002 and a unicast interfering signal 1014 from a second base station 1008. The first base station may be a macro eNB/cell with a first power class. The second base station may be a base station/cell (e.g., femto cell) with a second power class, such that the second power class is lower than the first power class.

At block 1104, the UE may convert the received composite signal from a time domain to a frequency domain. For example, the UE 1010 may perform an FFT on the received composite signal 1016 to convert the received composite signal 1016 from the time domain to the frequency domain.

At block 1106, the UE may estimate the unicast interfering signal from the frequency domain converted signal. In one aspect, the UE may estimate the unicast interfering signal by estimating or determining one or more relevant parameters related to unicast signal transmission. For example, the UE 1010 may estimate one or more of a unicast channel, traffic to pilot ratio, rank (i.e., number of layers), precoding matrix, transmission mode, modulation order, modulation symbol, and residual interference. In some instances, one or more of these parameters may be transmitted to the UE 1010 from a wireless network (e.g., via network assistance from the first base station 1002). Based on one or more of these parameters, the UE 1010 may estimate the unicast interfering signal 1014.

At block 1108, the UE may convert the estimated unicast interfering signal into a time domain interfering signal. For example, the UE 1010 may perform an IFFT on the estimated unicast interfering signal to convert the estimated unicast interfering signal from the frequency domain to the time domain.

Continuing with block 1108, the UE may convert the estimated unicast interfering signal from the frequency domain to the time domain under two configurations as shown in FIGS. 12A and 12B, which are flow charts of exemplary methods for improving MBMS coexistence in a network with multiple types of base stations using interference cancellation. In one configuration, the first base station transmits symbols with an extended prefix, and the second base station transmits symbols with a normal cyclic prefix. In this configuration, as shown in FIG. 12A, at block 1202, the UE may convert the estimated unicast interfering signal into a set of symbols in the time domain. For example, the UE 1010 may convert the estimated unicast interfering signal into a set of symbols in the time domain using IFFT. At block 1204, the UE may append a normal cyclic prefix to each symbol. At block 1206, the UE may append two or more cyclic prefix appended symbols together to obtain the time domain interfering signal. The number of cyclic prefix appended symbols may have a time duration equal to or greater than the time duration of the number of symbols in the composite signal from which interference is to be canceled. For example, the UE 1010 may append a normal cyclic prefix to each symbol of the estimated unicast interfering signal. Then, the UE 1010 may append two or more normal cyclic prefix appended symbols together such that the number of cyclic prefix appended symbols have a time duration equal to or greater than the time duration of the number of symbols in the composite signal 1016 from which interference is to be canceled.

In another configuration, the first base station transmits symbols with a normal cyclic prefix, and the second base station transmits symbols with an extended prefix. In this configuration, as shown in FIG. 12B, at block 1252, the UE may convert the estimated unicast interfering signal into a set of symbols in the time domain. For example, the UE 1010 may perform IFFT on the estimated unicast interfering signal to convert the estimated unicast interfering signal from the frequency domain to the time domain. At block 1254, the UE may append an extended cyclic prefix to each symbol. At block 1256, the UE may append one or more cyclic prefix appended symbols together to obtain the time domain interfering signal. The number of cyclic prefix appended symbols may have a time duration equal to or greater than the time duration of the number of symbols in the composite signal from which interference is to be canceled. For example, the UE 1010 may append an extended cyclic prefix to each symbol of the estimated unicast interfering signal. Then, the UE 1010 may append one or more normal cyclic prefix appended symbols together such that the number of cyclic prefix appended symbols have a time duration equal to or greater than the time duration of the number of symbols in the composite signal 1016 from which interference is to be canceled.

Referring back to FIG. 11, having obtained the time domain interfering signal, at block 1110, the UE may subtract the time domain interfering signal from the received composite signal to obtain the interference reduced signal. At block 1112, the UE may decode the interference reduced signal to obtain/recover an MBSFN transmission from the received composite signal. For example, the UE 1010 may convert the interference reduced signal to the frequency domain by performing FFT on the interference reduced signal and decode the interference reduced signal in the frequency domain.

FIG. 13 is a diagram 1300 illustrating an exemplary network architecture and method for improving MBMS coexistence in a network with different types of base stations. As shown in FIG. 13, a network may have a first base station (e.g., eNB3). The first base station may have a first power class. The network may also have other base stations with the first power class (e.g., eNB1, eNB2). The eNBs 1, 2, 3 may each be connected with one or more MME/S-GWs through an S1 interface, which has a user and control plane interface. The eNBs 1, 2, 3 may be connected to each other via a backhaul (e.g., an X2 interface). The network may also have a second base station (e.g., HeNB1, a femto cell) with a second power class. The second power class may be lower than the first power class. The network may also have other base stations with the second power class (e.g., HeNB2, HeNB3). The network may also have other types of base stations of different lower power classes such as pico cells, micro cells, or relay nodes. In one configuration, the second base station (e.g., HeNB1) may have an S1 interface with the MME/S-GW. In another configuration, the second base station (e.g., HeNB2, HeNB3) may have an S1 interface with a HeNB Gateway (HeNB GW). In this configuration, the HeNB GW may have an S1 interface with one or more MME/S-GWs. In yet another configuration, the second base station (e.g., HeNB3) may have an S5 interface with an MME/S-GW. The second base station and other base stations with the same power class (e.g., HeNB1, HeNB2, HeNB3) may also be connected via a backhaul (e.g., the X2 interface).

When a network, such as the one in FIG. 13, has multiple types of base stations with different power classes, there may be interference observed at the UE when the first base station of a first power class (e.g., the eNB3) transmits MBSFN signals for MBMS service on the same frequency that the second base station of a second power class (e.g., HeNB1) transmits unicast signals. As previously discussed, the UE may reduce some of the interference by receiving the MBMS service via a unicast signal from the second base station if the second base station is on the UE's CSG whitelist. Alternatively, the UE may reduce the interference by attempting to cancel at least some of the interference from the second base station. In addition to these methods, the interference may also be ameliorated by cooperation from the second base station, if the second base station is aware of the MBSFN subframes being utilized for MBMS transmission.

The second base station may cooperate with the first base station to improve MBMS coexistence in a network by transmitting MBSFN control signals to the UE. In one configuration, the second base station may perform network listening (e.g., behave like a UE and listen for transmissions from an eNB) and receive a SIB 2 from the first base station and determine the MBSFN subframes of the first base station based on the received SIB 2. In an aspect, the received SIB 2 may include information indicating which subframes are MBSFN subframes and/or which subframes are not MBSFN subframes. In another configuration, using network listening, the second base station may receive MSI from the first base station and determine the MBSFN subframes of the first base station based on the received MSI. The MSI may list which MBMS services are scheduled on which MBSFN subframes. By receiving the MSI, the second base station may know the occupied MBSFN subframes for MBMS service and may transmit MBSFN signals accordingly. In an aspect, an MCCH may reserve a set of MBSFN subframes, which may be more than all the services require, and the MSI may list all of the MBSFN subframes allocated to all services. In another configuration, using network listening, the second base station may receive SIB 13 from the first base station. The second base station may obtain the MBSFN configuration based on the received SIB 13. The second base station may also obtain an MCCH based on the received SIB 13. The second base station may obtain the MBSFN configuration based on the obtained MCCH and the SIB 13, and the MBSFN configuration would have information on the MBSFN subframes of the first base station. Of these options for obtaining information on the MBSFN subframes, the MSI may have more accurate information regarding MBSFN subframes used for MBMS compared to MCCH, SIB 13, and SIB 2.

Having determined the MBSFN subframes of the first base station, the second base station may determine, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals (e.g., user data) by the first base station. The second base station may determine the first and second set of symbols via network listening (e.g., listening to MCCH transmitted from the first base station). After this determination, the second base station may transmit unicast control information in a subset of the first set of symbols (e.g., in the unicast control region). The second base station may transmit unicast data with reduced power in the second set of symbols so as to reduce interference to the UE during MBSFN transmission. The reduced power may be zero power such that the second base station is effectively muting the unicast data in the second set of symbols. For example, the first base station may be an eNB, and the second base station may be a femto cell. The eNB may transmit MBSFN signals on a set of MBSFN subframes. The femto cell may determine which MBSFN subframes are being used by the eNB for MBSFN signal transmission by listening to SIB 13. In those MBSFN subframes, the femto cell may determine that the first 2 symbols are being used for control information and the remaining symbols are being used for MBSFN signals. As a result, in the MBSFN subframes, the femto cell may transmit unicast control information in the first symbol (or the first 2 symbols), and transmit unicast data with reduced power in the remaining data symbols. Alternatively, the femto cell may determine to mute the transmission of unicast data in the remaining data symbols. In one configuration, the second base station may not transmit SIB 13, an MCCH change notification, MCCH, or MTCH.

In another configuration, the second base station may transmit unicast control information in the first set of symbols and transmit unicast data with reduced power in the second set of symbols. In this configuration, the second base station may also transmit an MCCH change notification in the first set of symbols in the MBSFN subframes and/or transmit SIB 13 in non-MBSFN subframes, consistent with a SIB 13 and an MCCH change notification transmitted by the first base station. For example, the first base station may be an eNB, and the second base station may be a femto cell. The femto cell may transmit unicast data with reduced power in MBSFN subframes and also transmit SIB 13 on the PDSCH in non-MBSFN subframes. The femto cell may also transmit MCCH change notification on the PDCCH in the control symbols (e.g., the first set of symbols) of MBSFN subframes. In this configuration, the reception of system information and the control information by the UE may be more robust due to the transmissions by the femto cell.

In another configuration, the second base station may also transmit, in MBSFN subframes, an MCCH in the second set of symbols synchronously with the MCCH transmitted by the first base station. For example, the first base station may be an eNB, and the second base station may be a femto cell. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes, and, in MBSFN subframes, transmit unicast data with reduced power, an MCCH change notification on the PDCCH in the control symbols (e.g., the first set of symbols), and MCCH in data symbols (e.g., the second set of symbols) synchronously with the MCCH transmitted by the eNB. In this configuration, the MCCH has also been made more robust by the femto cell based on the joint transmissions by the femto cell and the eNB.

In such a method, synchronization between the first base station and the second base station may be needed. In TDD, the second base station may be synchronized to the first base station (e.g., within 3 μs accuracy). In FDD, the second base station can be synchronized to the network. By listening to the network, the second base station can synchronize certain transmissions with the network. Thus, subframe boundaries and system frame numbers (SFNs) of the first base station and the second base station would be aligned.

FIG. 14A is a diagram 1400 illustrating network architecture configured to provide MBMS service. As shown in FIG. 14A, a first base station (e.g., the eNB) is connected to an MBMS-GW via an M1 interface. The M1 interface is the user plane interface through which user data may be provided to the first base station from a BM-SC through the MBMS-GW. The first base station may also be connected to an MCE via an M2 interface. The M2 interface is a E-UTRAN internal control plane interface through which control information may be provided to the first base station from an MME through the MCE. The MCE is connected to the MME through the M3 interface, which is the control plane interface between the E-TRAN and the EPC. One method of providing MBMS service awareness to lower power class base stations for purposes of base station cooperation is to extend the MBMS network architecture to the lower power class base stations as shown in FIG. 14B.

FIG. 14B is a diagram 1450 illustrating an exemplary network architecture and method for improving MBMS coexistence in a network with multiple types of base stations through base station cooperation. As illustrated in FIG. 14B, lower power base stations may cooperate with higher power base stations to improve MBMS coexistence in a network based on received operation and management (O&M) configurations. In FIG. 14B, a first base station (e.g., eNB) has a first power class, and a second base station (e.g., HeNB or femto cell) has a second power class. The second power class may be lower than the first power class. The first base station may be connected to the MCE via the M2 interface and connected to the MBMS GW via the M1 interface. Unlike in FIG. 14A, however, in FIG. 14B, the M1 and M2 interfaces have been extended from the MBMS GW and MCE, respectively, to the second base station. The M1 and M2 interface may be extended directly to the second base station or indirectly to the second base station through the HeNB GW for additional security. The second base station may be connected to the BM-SC through a backhaul link (e.g., DSL/cable) for purposes of receiving MBSFN data. An HeNB management system (HMS) may be used for configuring the second base station such that the second base station is aware of the MBSFN subframes and other MBMS configuration information.

Referring to FIG. 14B, the first base station may be transmitting MBSFN signals to a UE on the same frequency that the second base station transmits unicast signals. As a result, reception of an MBMS transmission at the UE may suffer from interference due to the unicast transmission. In an attempt to reduce the interference, the second base station may cooperate with the first base station.

An MBMS session may be set up between the BM-SC and the second base station. In one aspect, the MBMS session may be initiated by the BM-SC. In this aspect, the BM-SC may transmit a session start request and the second base station may transmit a session start response to set up the MBMS session. In another aspect, the MBMS session may be initiated by the second base station. In this aspect, the second base station may listen for MBSFN signals for an MBMS service from the first base station and, upon detecting the MBSFN signals, send an MBMS session start initiation to the BM-SC through a MCE, a MME, and a MBMS GW to initiate an MBMS session associated with the MBMS service. Subsequently, the second base station may receive a response to the MBMS session start initiation for purposes of setting up an MBMS session. In both aspects, the second base station may perform the above steps (e.g., send an initiation message and receive a response or receive an initiation message and send a response) to join the same MBMS session as the first base station. Having joined the MBMS session, the second base station may receive MBMS content (e.g., data and/or control information) from the BM-SC via a synchronization protocol. Also, the second base station may receive information from the HMS. The information received from the HMS may include information such as MBSFN configuration information, the number of MBSFN subframes being used by the first base station, the number of control symbols being used in an MBSFN subframe, and the MCCH configuration, etc. Based on some or all of the information received from the HMS, the second base station may determine the MBSFN subframes of the first base station. The second base station may determine the frequency at which the first base station transmits the MBSFN signals (e.g., based on the MBSFN configuration information). The second base station may also determine, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals (e.g., user data) by the first base station. In one aspect, the second base station may determine the first and second set of symbols via backhaul communication between the BM-SC and the second base station or via backhaul communication between the first base station and the second base station. In another aspect, the second base station may determine the first and second symbols based on network listening in which the second base station listens to the MCCH transmitted by the first base station. The first set of symbols may include one or two symbols. After this determination, the second base station may transmit unicast control information in a subset of the first set of symbols at the determined frequency that the first base station transmits MBSFN signals. The second base station may transmit unicast data at the same determined frequency with reduced power in the second set of symbols so as to reduce interference to the UE during MBSFN transmission. The reduced power may be zero power such that the second base station is effectively muting the unicast data in the second set of symbols.

For example, the first base station may be an eNB and the second base station may be a femto cell. The eNB may transmit MBSFN signals to provide MBMS service to a UE. The femto cell may be causing interference to the UE by simultaneously transmitting unicast signals on the same frequency that the eNB is transmitting MBSFN signals. To reduce interference, the femto cell may cooperate with the eNB. In one example, an MBMS session may be set up (or initiated) between a BM-SC and the femto cell. In another example, the femto cell may listen for MBSFN signals, and upon the detection of MBSFN signals, send an MBMS session start initiation to the BM-SC through an MCE, an MME, and an MBMS GW to initiate an MBMS session. Once the MBMS session is initiated, the femto cell may receive information from the HMS, and such information may include MBSFN configuration information (e.g., a frequency at which the MBSFN signals are transmitted by the eNB). Based on the received information from the HMS, the femto cell may determine which MBSFN subframes are being used by the eNB for MBSFN signal transmission. In those MBSFN subframes, the femto cell may determine that 2 symbols are being used for control information and the remaining symbols are being used for MBSFN signals. As a result, the femto cell may transmit unicast control information in a subset of the 2 symbols (e.g., on the first symbol), and transmit unicast data with reduced power in the remaining data symbols. In an aspect, the unicast control information and the unicast data may be transmitted at the frequency of the MBSFN signals. Alternatively, the femto cell may determine to mute the transmission of unicast data in the remaining data symbols.

In one configuration, the second base station may also transmit SIB 13 in non-MBSFN subframes and/or transmit an MCCH change notification in the first set of symbols in MBSFN subframes, consistent with a SIB 13 and/or an MCCH change notification transmitted by the first base station. For example, in this configuration, the first base station may be an eNB and the second base station may be a femto cell. In the MBSFN subframes, the femto cell may transmit unicast data on reduced power. The femto cell may transmit MCCH change notification on the PDCCH in the controls symbols (e.g., the first set of symbols) of the MBSFN subframe. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes.

In another configuration, the second base station may also transmit an MCCH in the second set of symbols synchronously with the MCCH transmitted by the first base station. The second base station may obtain the MCCH from the BM-SC or by listening to the MCCH from the first base station. Because the second base station transmits the MCCH synchronously with the MCCH of the first base station, the second base station may transmit the MCCH on the same symbol(s) and subcarrier(s) as used by the first base station. The second base station may determine the symbol(s) and subcarrier(s) used by the first base station for transmitting MCCH based on backhaul communication with the BM-SC or the first base station or via network listening for the MCCH. For example, in this configuration, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes, and in MBSFN subframes, transmit unicast data on reduced power, MCCH change notification on the PDCCH in the control symbols (e.g., the first set of symbols), and MCCH in the data symbols (e.g., the second set of symbols). The femto cell may transmit the MCCH synchronously with the MCCH transmitted by the eNB.

In another configuration, the second base station may also transmit MTCH in the second set of symbols synchronously with the MTCH transmitted by the first base station. The second base station may obtain the MTCH from the BM-SC. For example, in this configuration, the first base station may be an eNB and the second base station may be femto cell. Also, the first set of symbols may be referred to as control symbols for transmitting control information and the second set of symbols may be referred to as data symbols for transmitting MBSFN data. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes. In MBSFN subframes, the femto cell may transmit MCCH change notification on the PDCCH in the control symbols, transmit MCCH in data symbols synchronously with the MCCH transmitted by the eNB, and/or transmit MTCH in data symbols synchronously with the MTCH transmitted by the eNB. In this configuration, the second base station (e.g., femto cell) is functioning like the first base station (e.g., eNB) because the second base station is able to transmit MBSFN control signals via information received from the M2 interface as well as user data received from the M1 interface. Thus, by participating in the transmission of either MBSFN control information and/or MBSFN data to the UE, the second base station may increase the likelihood that the UE can successfully receive MBMS service.

FIG. 15 is a flow chart 1500 of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations. The method may be performed by a second base station (e.g., femto cell, pico cell, relay node) having a second power class. At block 1502, the second base station may listen for MBSFN signals for MBMS service from a first base station (e.g., an eNB) having a first power class. The second power class may be lower than the first power class. Upon detecting the MBSFN signals, the second base station may send an MBMS session start initiation to the BM-SC through an MCE, an MME, and an MBMS GW. In response to the MBMS session start initiation, the BM-SC may set up an MBMS session with the second base station following existing MBMS setup procedures. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may detect MBSFN signals for MBMS service from the eNB. Upon detecting the MBSFN signals, the femto cell may send an MBMS session start initiation to the BM-SC through an MCE, an MME, and an MBMS GW. In response, the BM-SC may set up an MBMS session with the femto cell following existing MBMS setup procedures. In another configuration, however, the MBMS session may be initiated by the BM-SC.

At block 1504, the second base station may initiate or join an MBMS session associated with a BM-SC. For example, the second base station may be a femto cell. The femto cell may initiate an MBMS session with a BM-SC by sending an MBMS session start initiation message to initiate the MBMS session. In another example, the BM-SC may initiate an MBMS session, and the femto cell may join the MBMS session. In both examples, an MBMS session is set up between the BM-SC and the femto cell.

At block 1506, the second base station may receive information from the HMS. The information received from the HMS may include information such as MBSFN configuration information, the number of MBSFN subframes being used by the first base station, the number of control symbols being used in an MBSFN subframe, and the MCCH configuration, etc.

At block 1508, based on the information received from the HMS, the second base station may determine the MBSFN subframes transmitted by the first base station. The second base station may also determine, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals (e.g., user data) by the first base station. In particular, the second base station may determine resources (e.g., determine specific symbols and subcarriers) used by the first base station for transmitting MCCH. The second base station may determine additional resources (e.g., determine specific symbols and subcarriers) used by the first base station for transmitting MTCH. For example, the first base station may be an eNB and the second base station may be a femto cell. In this example, based on the received information from the HMS, the femto cell may determine which MBSFN subframes are being used by the eNB for MBSFN signal transmission. In those MBSFN subframes, the femto cell may determine that 2 symbols are being used for control information and the remaining data symbols are being used for MBSFN signals. More specifically, the femto cell may determine the symbols and subcarriers used by the eNB for transmitting MCCH and/or MTCH.

At block 1510, the second base station may transmit unicast control information in a subset of the first set of symbols. The second base station may transmit unicast data with reduced power in the second set of symbols so as to reduce interference with the MBSFN transmission at the UE. The reduced power may be zero power such that the second base station is effectively muting the unicast data in the second set of symbols. For example, the first base station may be an eNB, and the second base station may be a femto cell. The femto cell may transmit unicast control information in a subset of the 2 symbols (e.g., on the first symbol or the first 2 symbols), and transmit unicast data with reduced power in the remaining data symbols. Alternatively, the femto cell may determine to mute the transmission of unicast data in the remaining data symbols.

At block 1512, the second base station may transmit at least one of a SIB 13 in non-MBSFN subframes, an MCCH change notification in the first set of symbols, an MCCH in the second set of symbols, and/or an MTCH in the second set of symbols. For example, the second base station may be a femto cell. The femto cell may transmit a SIB 13 in non-MBSFN subframes and an MCCH change notification in the first set of symbols.

FIG. 16 is a diagram 1600 illustrating an exemplary network architecture and method for improving MBMS coexistence in a network with multiple types of base stations through base station cooperation. In FIG. 16, a first base station (e.g., eNB) has a first power class, and a second base station (e.g., HeNB) has a second power class. The second power class may be lower than the first power class. The first base station may be connected to the MCE via the M2 interface and connected to the MBMS GW via the M1 interface. The second base station may be directly connected to the MBMS GW via the M1 interface and/or indirectly connected to the MGMS GW through the HeNB GW. However, the second base station is not connected to the MCE via an M2 interface. The first base station may be transmitting MBSFN signals to the UE on the same frequency that the second base station is transmitting unicast signals. As a result, the UE may suffer from interference as a result of the unicast transmission. In an attempt to reduce the interference, the second base station may cooperate with the first base station.

In FIG. 16, unlike in FIG. 14B, the second base station is not connected to the MCE via an M2 interface. As a result, the second base station cannot cooperate with the first base station based on MBSFN configuration information received directly from the MCE. Nevertheless, the second base station may cooperate with the first base station through network listening. The second base station may receive user service description (USD) bootstrapping information. The USD bootstrapping information may be received from the network or may be preconfigured. Based on the USD bootstrapping information, the second base station may obtain or receive a USD via a unicast transmission or via an MBMS session. For example, to receive the USD via unicast, the second base station may be preconfigured with a unicast server IP address or an URL and fetch the USD through a unicast channel from a server. Alternatively, to receive the USD via MBMS transmission, the second base station may receive or be preconfigured with the USD bootstrapping information. The USD bootstrapping information may provide the specific TMGI associated with the USD, and the second base station may use the specific TMGI to listen to the MBMS transmission to obtain the USD from an MBMS bearer. The USD may contain a session description protocol (SDP) associated with an MBMS session. The SDP may include a multicast IP address and a sender source IP address associated with an MBMS session. Thus, after obtaining the USD, the second base station may obtain the multicast IP address and the source IP address from the USD (e.g., from the SDP in the USD). With the multicast IP address and the source IP address, the second base station may join the multicast tree from the first base station. After joining the multicast tree, the second base station may perform network listening and receive a SIB 2 from the first base station. The second base station may receive an MSI from the first base station. The second base station may receive SIB 13 from the first base station. The second base station may obtain the MBSFN configuration based on the received SIB 13. The second base station may also obtain an MCCH based on the received SIB 13. The second base station may obtain the MBSFN configuration based on the obtained MCCH and the SIB 13. The MBSFN configuration would have information on the MBSFN subframes of the first base station. The second base station may also determine the MBSFN subframes of the first base station based on the received SIB 2 and/or the received MSI. MSI may have more accurate information regarding MBSFN subframes used for MBMS compared to MCCH, SIB 13, and SIB 2.

Having determined the MBSFN subframes of the first base station, the second base station may determine, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals (e.g., user data) by the first base station. The first set of symbols may include one or two symbols. The second base station may determine the first and second set of symbols used for control information and for MBSFN signals, respectively, based on the MCCH received through network listening. The MCCH (and/or SIB 13) may also indicate specific symbols and/or subcarriers used by the first base station for transmitting MCCH and/or MTCH. After this determination, the second base station may transmit unicast control information in a subset of the first set of symbols. The second base station may transmit unicast data with reduced power in the second set of symbols so as to reduce interference to the UE during MBSFN transmission. The reduced power may be zero power such that the second base station is effectively muting the unicast data in the second set of symbols. For example, the first base station may be an eNB and the second base station may be a femto cell. The eNB may transmit on MBSFN signals to provide MBMS service to a UE. The femto cell may be causing interference to the UE by simultaneously transmitting unicast signals on the same frequency that the eNB is transmitting MBSFN signals. To reduce interference, the femto cell may cooperate with the eNB by performing network listening. The femto cell may be preconfigured with or may receive from the network USD bootstrapping information. Based on the USD bootstrapping information, the femto cell may obtain or receive a USD from unicast or MBMS via the eNB. After obtaining the USD, the femto cell may obtain a multicast IP address and a source IP address from the USD. With the multicast IP address and source IP address, the femto cell may join the multicast tree from the eNB. After joining the multicast tree, the femto cell may perform network listening and receive a SIB 2, MSI, and SIB 13 from the eNB. The femto cell may obtain MCCH based on the received SIB 13. The femto cell may obtain the MBSFN configuration based on the obtained MCCH and the SIB 13, and the MBSFN configuration would have information on the MBSFN subframes being used by the eNB. The femto cell may also determine the MBSFN subframes based on the received SIB 2 and/or the received MSI.

Having determined the MBSFN subframes of the eNB, the femto cell may determine, in the MBSFN subframes, a first set of symbols used for control information by the eNB and a second set of symbols used for MBSFN signals (e.g., user data) by the eNB. The femto cell may determine that 2 symbols are being used for control information and the remaining data symbols are being used for MBSFN signals. The femto cell may also determine the subcarriers in the symbols used by the first base station for transmitting MCCH and/or MTCH. As a result, in the MBSFN subframes, the femto cell may transmit unicast control information in a subset of the two symbols (e.g., the first two symbols), and transmit unicast data with reduced power in the remaining data symbols. Alternatively, the femto cell may determine to mute the transmission of unicast data in the remaining data symbols.

In one configuration, the second base station may also transmit SIB 13 in non-MBSFN subframes. In MBSFN subframes, the second base station may transmit an MCCH change notification in the first set of symbols. The SIB 13 and the MCCH change notification may be transmitted with a SIB 13 and an MCCH change notification transmitted by the first base station. In this configuration, the second base station may transmit via unicast the same SIB 13 and MCCH change notification content as the first base station. However, the resources used by the second base station to transmit the SIB 13 and MCCH change notification need not be the same resources used by the first base station for transmitting the SIB 13 and MCCH change notification. For example, in this configuration, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may transmit unicast data with reduced power in the MBSFN subframes. The femto cell may also transmit SIB 13 on the PDSCH in non-MBSFN subframes and/or an MCCH change notification on the PDCCH in the first 2 symbols in the MBSFN subframes. In an aspect, the resources used by the femto cell to transmit the SIB 13 and MCCH change notification need not be the same resources used by the eNB for transmitting the SIB 13 and MCCH change notification.

In another configuration, the second base station may also transmit an MCCH in the second set of symbols synchronously with the MCCH transmitted by the first base station. In this configuration, the second base station may determine the resources within the second set of symbols used by the first base station for transmitting the MCCH. The resources may include the data symbol(s) and the sub-carrier(s) within the MBSFN subframe used by the first base station for transmitting the MCCH. For example, the first base station may be an eNB, and the second base station may be a femto cell. The femto cell may transmit unicast data on reduced power in the MBSFN subframes. The femto cell may transmit an MCCH change notification on the PDCCH in the first 2 symbols of the MBSFN subframes. The femto cell may determine the data symbols (e.g., the second set of symbols) and the corresponding sub-carriers of the MBSFN subframes that the eNB uses for transmitting the MCCH. The femto cell may transmit MCCH in data symbols of the MBSFN subframes synchronously (e.g., in the same data symbols and the same sub-carriers) with the MCCH transmitted by the eNB. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes.

In another configuration, having joined the multicast group upon receiving MBSFN configuration and having an M1 interface with the MBMS GW to receive MBMS content, the second base station may also transmit MTCH in the second set of symbols synchronously with the MTCH transmitted by the first base station. In one aspect, the MTCH may be transmitted by the second based station based on the obtained MBSFN configuration and the M1 interface with the MBMS GW. In this configuration, the second base station may determine additional resources within the second set of symbols used by the first base station for transmitting the MTCH. The additional resources may include the data symbol(s) and the sub-carrier(s) within the MBSFN subframe used by the first base station for transmitting the MTCH. For example, the first base station may be an eNB, and the second base station may be a femto cell. The femto cell may transmit unicast data on reduced power in MBSFN subframes. The femto cell may determine the data symbols and the corresponding sub-carriers of the MBSFN subframes that the eNB uses for transmitting the MTCH. The femto cell may also transmit MCCH change notification on the PDCCH in the first 2 symbols of the MBSFN subframes, transmit an MCCH in data symbols synchronously (e.g., in the same data symbols and the same sub-carriers as used by the eNB) with the MCCH transmitted by the eNB, and transmit an MTCH in data symbols synchronously (e.g., in the same data symbols and the same sub-carriers as used by the eNB) with the MTCH transmitted by the eNB. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes. In this configuration, the femto cell is functioning like the eNB because the femto cell is able to transmit MBSFN control signals and data upon joining the multicast group/tree. Thus, by participating in the transmission of either MBSFN control information and/or data to the UE, the femto cell may increase the likelihood that the UE can successfully receive MBMS service. Furthermore, by receiving the MBSFN configuration through network listening, dynamic changes in the MBSFN configuration may be easily detected.

FIG. 17 is a flow chart 1700 of an exemplary method of improving MBMS coexistence in a network with multiple types of base stations. The method may be performed by a second base station (e.g., femto cell, pico cell, relay node) having a second power class. At block 1702, the second base station may receive user service description (USD) bootstrapping information. The USD bootstrapping information may be received from the network or be preconfigured. For example, the second base station may be a femto cell. The femto cell may be preconfigured with or may receive from the network USD bootstrapping information.

At block 1704, based on the USD bootstrapping information, the second base station may obtain or receive a USD from via a unicast transmission or an MBMS service. After obtaining the USD, the second base station may obtain a multicast IP address and a source IP address from the USD. With the multicast IP address and the source IP address, the second base station may join the multicast tree from the first base station. For example, the first base station may be an eNB, and the second base station may be a femto cell. Based on the USD bootstrapping information, the femto cell may obtain or receive a USD from unicast or MBMS via the eNB. After obtaining the USD, the femto cell may obtain a multicast IP address and a source IP address from the USD. With the multicast IP address and source IP address, the femto cell may join the multicast tree from the eNB.

At block 1706, the second base station may perform network listening and receive a SIB 2 from the first base station. The second base station may determine the MBSFN subframes based on the received SIB 2. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may receive a SIB 2 from the eNB.

At block 1708, the second base station may receive an MSI from the first base station. The second base station may determine the MBSFN subframes based on the received MSI. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may receive an MSI from the eNB.

At block 1710, the second base station may receive SIB 13 from the first base station. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may receive a SIB 13 from the eNB.

At block 1712, the second base station may obtain the MBSFN configuration based on the received SIB 13. The second base station may also obtain an MCCH based on the received SIB 13. The second base station may obtain the MBSFN configuration based on the obtained MCCH and the SIB 13. The MBSFN configuration would have information on the MBSFN subframes of the first base station. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may obtain the MCCH based on the received SIB 13. The femto cell may obtain the MBSFN configuration based on the obtained MCCH and the SIB 13, and the MBSFN configuration would have information on the MBSFN subframes being used by the eNB. The femto cell may also determine the MBSFN subframes based on the received SIB 2 and/or the received MSI.

At block 1714, the second base station may determine, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals (e.g., user data) by the first base station. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may determine, in the MBSFN subframes, a first set of symbols used for control information and a second set of symbols used for MBSFN signals (e.g., user data). The femto cell may determine the MBSFN subframes used by the eNB based on an MCCH (and/or SIB 13) received from the eNB. And the femto cell may determine the first set of symbols used for control information and the second set of symbols used for MBSFN signals based on the MCCH (and/or SIB 13) received from the eNB. In particular, the MCCH may indicate resources (e.g., data symbols and subcarriers) within the second set of symbols used for MBSFN signals (e.g., for transmitting MTCH). The femto cell may determine that 2 symbols are being used for control information and the remaining symbols are being used for MBSFN signals.

At block 1716, the second base station may determine resources within the second set of symbols used by the first base station for transmitting an MCCH. The second base station may also determine additional resources within the second set of symbols used by the first base station for transmitting an MTCH. For example, the first base station may be an eNB and the second base station may be a femto cell. The femto cell may determine the symbols and sub-carriers within the second set of symbols used by the eNB for transmitting the MCCH based on an MCCH or SIB 13 received from the eNB. The femto cell may also determine the symbols and sub-carriers within the second set of symbols used by the eNB for transmitting the MTCH based on an MCCH received from the eNB. As discussed above, the femto cell may obtain the MCCH from the eNB based on a received SIB 13, and the MCCH may indicate the resources (e.g., symbols and subcarriers) on which the MCCH is transmitted by the eNB and may indicate the additional resources on which the MTCH is transmitted by the eNB.

At block 1718, the second base station may transmit unicast control information in a subset of the first set of symbols. The unicast control information may be transmitted at a frequency that the first base station is using for providing MBMS service. The second base station may transmit unicast data with reduced power in the second set of symbols so as to reduce interference to the UE during MBSFN transmission. The unicast data may be transmitted at a frequency that the first base station is using for providing MBMS service. The reduced power may be zero power such that the second base station is effectively muting the unicast data in the second set of symbols. For example, the first base station may be an eNB, and the second base station may be a femto cell. In an MBSFN subframe, the femto cell may transmit unicast control information in a subset of the two symbols (e.g., the first two symbols), and transmit unicast data with reduced power in the remaining data symbols. Alternatively, the femto cell may determine to mute the transmission of unicast data in the remaining data symbols.

At block 1720, the second base station may transmit, at the frequency at which the first base station is transmitting MBSFN signals, at least one of a SIB 13 in non-MBSFN subframes, an MCCH change notification in the first set of symbols, an MCCH in the second set of symbols, or an MTCH in the second set of symbols. For example, the first base station may be an eNB, and the second base station may be a femto cell. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN subframes, and in MBSFN subframes, transmit unicast data on reduced power, transmit an MCCH change notification on PDCCH in the first 2 symbols of the MBSFN subframes, and transmit an MCCH in data symbols synchronously (e.g., within the same data symbols and sub-carriers as the eNB) with the MCCH transmitted by the eNB.

FIG. 18 is a conceptual data flow diagram 1800 illustrating the data flow between different modules/means/components in an exemplary apparatus 1802. The apparatus may be a UE. The apparatus includes an RRC state module 1806 that may be configured to maintain an RRC idle state with the first base station 1812. The apparatus includes a reception module 1804 that may be configured to determine that the UE is in range of the second base station 1814. The second base station 1814 may have a second power class. The RRC state module 1806 may be configured to establish an RRC connected state with a first base station 1812. The first base station 1812 may have a first power class, and the first power class may be greater than the second power class. The RRC state module 1806 may be configured to establish an RRC connected state with the first base station 1812 through the transmission module 1810. The RRC state module 1806 may be configured to move in a handoff from the first base station 1812 to the second base station 1814 upon determining that the UE is in range of the second base station 1814. The reception module 1804 and transmission module 1810 may be configured to communicate with a second base station 1814 in an RRC connected state. The reception module 1804 may be configured to receive MBMS service from a first base station 1812 while in an RRC connected state with the second base station 1814. The apparatus includes a decode module 1808 that may be configured to determine that the apparatus is unable to decode MBSFN signals of the MBMS service from the first base station 1812. The reception module 1804 may be configured to receive the MBMS service from the second base station 1814 through a unicast channel upon determining that the apparatus is unable to decode the MBSFN signals of the MBMS service from the first base station 1812.

The apparatus may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow charts of FIG. 9. As such, each block in the aforementioned flow charts of FIG. 9 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 19 is a diagram 1900 illustrating an example of a hardware implementation for an apparatus 1802′ employing a processing system 1914. The processing system 1914 may be implemented with a bus architecture, represented generally by the bus 1924. The bus 1924 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1914 and the overall design constraints. The bus 1924 links together various circuits including one or more processors and/or hardware modules, represented by the processor 1904, the reception module 1804, the RRC state module 1806, the decode module 1808, the transmission module 1810, and the computer-readable medium/memory 1906. The bus 1924 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1914 may be coupled to a transceiver 1910. The transceiver 1910 is coupled to one or more antennas 1920. The transceiver 1910 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1910 receives a signal from the one or more antennas 1920, extracts information from the received signal, and provides the extracted information to the processing system 1914, specifically the reception module 1804. In addition, the transceiver 1910 receives information from the processing system 1914, specifically the transmission module 1810, and based on the received information, generates a signal to be applied to the one or more antennas 1920. The processing system 1914 includes a processor 1904 coupled to a computer-readable medium/memory 1906. The processor 1904 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1906. The software, when executed by the processor 1904, causes the processing system 1914 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1906 may also be used for storing data that is manipulated by the processor 1904 when executing software. The processing system further includes at least one of the modules 1804, 1806, 1808, and 1810. The modules may be software modules running in the processor 1904, resident/stored in the computer readable medium/memory 1906, one or more hardware modules coupled to the processor 1904, or some combination thereof. The processing system 1914 may be a component of the UE 650 and may include the memory 660 and/or at least one of the TX processor 668, the RX processor 656, and the controller/processor 659.

In one configuration, the apparatus 1802/1802′ for wireless communication includes means for communicating with a second base station in an RRC connected state. The apparatus 1802/1802′ may include means for receiving an MBMS service from a first base station while in an RRC connected state with the second base station. The first base station has a first power class, and the second base station has a second power class lower than the first power class. The apparatus may include means for determining that the apparatus is unable to decode MBSFN signals of the MBMS service from the first base station. For example, the signal to noise ratio from the first base station may be below a threshold, or the block error rate may be too high. The apparatus may include means for receiving the MBMS service from the second base station through a unicast channel upon determining that the apparatus is unable to decode the MBSFN signals of the MBMS service from the first base station. The apparatus may include means for maintaining an RRC idle state with the first base station. The apparatus may include means for determining that the apparatus is in range of the second base station. For example, the apparatus may detect signals from the second base station. The apparatus may include means for establishing an RRC connected state with the first base station. The apparatus may include means for moving in a handoff from the first base station to the second base station upon determining that the UE is in range of the second base station.

The aforementioned means may be one or more of the aforementioned modules of the apparatus 1802 and/or the processing system 1914 of the apparatus 1802′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1914 may include the TX Processor 668, the RX Processor 656, and the controller/processor 659. As such, in one configuration, the aforementioned means may be the TX Processor 668, the RX Processor 656, and the controller/processor 659 configured to perform the functions recited by the aforementioned means.

FIG. 20 is a conceptual data flow diagram 2000 illustrating the data flow between different modules/means/components in an exemplary apparatus 2002. The apparatus may be a UE. The apparatus includes a reception module 2004 that may be configured to receive a composite signal that includes a MBSFN signal from a first base station 2012 and a unicast interfering signal from a second base station 2014. The first base station 2012 has a first power class. The second base station 2014 has a second power class. The second power class may be lower than the first power class. The apparatus includes a conversion/subtraction module 2008 that may be configured to convert the received composite signal from a time domain to a frequency domain (e.g., by performing an FFT). The apparatus includes an estimation module 2006 that may be configured to estimate the unicast interfering signal from the frequency domain converted signal. The conversion/subtraction module 2008 may be configured to convert the estimated unicast interfering signal into a time domain interfering signal (e.g., by performing IFFT).

In one configuration, the first base station 2012 transmits symbols with an extended cyclic prefix, the second base station 2014 transmits symbols with a normal cyclic prefix, the conversion/subtraction module 2008 may be configured to convert the estimated unicast interfering signal into a set of symbols in the time domain. The conversion/subtraction module 2008 may also be configured to append a normal cyclic prefix to each symbol. The conversion/subtraction module 2008 may also be configured to append two or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

In another configuration, the first base station 2012 transmits symbols with a normal cyclic prefix, the second base station 2014 transmits symbols with an extended cyclic prefix, the conversion/subtraction module 2008 may be configured to convert the estimated unicast interfering signal into a set of symbols in the time domain. The conversion/subtraction module 2008 may also be configured to append an extended cyclic prefix to each symbol. The conversion/subtraction module 2008 may also be configured to append one or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

The conversion/subtraction module 2008 may be configured to subtract the time domain interfering signal from the received composite signal to obtain an interference reduced signal. The apparatus may include a decode module 2010 that may be configured to decode the interference reduced signal to obtain an MBSFN transmission.

The apparatus may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow charts of FIGS. 11 and 12. As such, each block in the aforementioned flow charts of FIGS. 11 and 12 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 21 is a diagram 2100 illustrating an example of a hardware implementation for an apparatus 2002′ employing a processing system 2114. The processing system 2114 may be implemented with a bus architecture, represented generally by the bus 2124. The bus 2124 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2114 and the overall design constraints. The bus 2124 links together various circuits including one or more processors and/or hardware modules, represented by the processor 2104, the reception module 2004, the estimation module 2006, the conversion/subtraction module 2008, the decode module 2010, and the computer-readable medium/memory 2106. The bus 2124 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2114 may be coupled to a transceiver 2110. The transceiver 2110 is coupled to one or more antennas 2120. The transceiver 2110 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2110 receives a signal from the one or more antennas 2120, extracts information from the received signal, and provides the extracted information to the processing system 2114, specifically the reception module 2004. In addition, the transceiver 2110 receives information from the processing system 2114, and based on the received information, generates a signal to be applied to the one or more antennas 2120. The processing system 2114 includes a processor 2104 coupled to a computer-readable medium/memory 2106. The processor 2104 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 2106. The software, when executed by the processor 2104, causes the processing system 2114 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 2106 may also be used for storing data that is manipulated by the processor 2104 when executing software. The processing system further includes at least one of the modules 2004, 2006, 2008, and 2010. The modules may be software modules running in the processor 2104, resident/stored in the computer readable medium/memory 2106, one or more hardware modules coupled to the processor 1304, or some combination thereof. The processing system 2114 may be a component of the UE 650 and may include the memory 660 and/or at least one of the TX processor 668, the RX processor 656, and the controller/processor 659.

In one configuration, the apparatus 2002/2002′ for wireless communication includes means for receiving a composite signal including an MBSFN signal from a first base station and a unicast interfering signal from a second base station. The first base station has a first power class, and the second base station has a second power class that is lower than the first power class. The apparatus may include means for converting the received composite signal from a time domain to a frequency domain. The apparatus may include means for estimating the unicast interfering signal from the frequency domain converted signal. The apparatus may include means for converting the estimated unicast interfering signal into a time domain interfering signal. The apparatus may include means for subtracting the time domain interfering signal from the received composite signal to obtain an interference reduced signal. The apparatus may include means for decoding the interference reduced signal to obtain an MBSFN transmission.

In one configuration, when the first base station transmits symbols with an extended cyclic prefix, and the second base station transmits symbols with a normal cyclic prefix, the means for converting the estimated unicast interfering signal may be configured to convert the estimated unicast interfering signal into a set of symbols in the time domain, append a normal cyclic prefix to each symbol, and append two or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

In another configuration, when the first base station transmits symbols with a normal cyclic prefix, and the second base station transmits symbols with an extended cyclic prefix, the means for converting the estimated unicast interfering signal may be configured to convert the estimated unicast interfering signal into a set of symbols in the time domain, append a normal cyclic prefix to each symbol, and append two or more cyclic prefix appended symbols together to obtain the time domain interfering signal.

The aforementioned means may be one or more of the aforementioned modules of the apparatus 2002 and/or the processing system 2114 of the apparatus 2002′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system 2114 may include the TX Processor 668, the RX Processor 656, and the controller/processor 659. As such, in one configuration, the aforementioned means may be the TX Processor 668, the RX Processor 656, and the controller/processor 659 configured to perform the functions recited by the aforementioned means.

FIG. 22 is a conceptual data flow diagram 2200 illustrating the data flow between different modules/means/components in an exemplary apparatus 2202. The apparatus may be a base station (e.g., a femto cell). The apparatus includes a reception module 2204, an MBSFN configuration module 2206, an MBMS session control module 2208, and a transmission module 2210. The MBSFN configuration module 2206 may be configured to determine MBSFN subframes at a frequency of a first base station. The first base station has a first power class, and the apparatus has a second power class. The second power class may be lower than the first power class. The MBSFN configuration module 2206 may be configured to determine, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals by the first base station. The transmission module 2210 may be configured to transmit, at the frequency, unicast control information in a subset of the first set of symbols. The transmission module 2210 may be configured transmit, at the frequency, unicast data with a reduced power in the second set of symbols. The transmission module 2210 may be configured to transmit, at the frequency, SIB 13 in non-MBSFN subframes and an MCCH change notification in the first set of symbols with a SIB 13 and an MCCH change notification transmitted by the first base station. The MBSFN configuration module 2206 may be configured to determine resources within the second set of symbols used by the first base station for transmitting the MCCH. The MBSFN configuration module 2206 may be configured to determine additional resources within the second set of symbols used by the first base station for transmitting the MTCH. The transmission module 2210 may be configured to transmit, synchronously with the first base station at the frequency, the MCCH in the second set of symbols synchronously (e.g., within the determined resources) with the MCCH transmitted by the first base station. The transmission module 2210 may be configured to transmit, synchronously with the first base station at the frequency, the MTCH in the second set of symbols synchronously (e.g., within the determined additional resources) with the MTCH transmitted by the first base station.

In one configuration, the MBMS session control module 2208 may be configured to join an MBMS session associated with a BM-SC. In this configuration, the apparatus may have an M1 interface with an MBMS gateway and an M2 interface with an MCE.

In another configuration, the reception module 2204 may be configured to receive USD bootstrapping information, the MBSFN configuration module 2206 may be configured to obtain a USD based on the USD bootstrapping information and a multicast IP address and a source IP address from the USD, in which the SIB 13, MCCH change notification, MCCH, and MTCH is based on the obtained multicast IP address and the obtained source IP address. In this configuration, the apparatus may have an M1 interface with an MBMS gateway.

In another configuration, the transmission module 2210 may be configured to send an MBMS session start initiation to a BM-SC through the MCE, the MME, and the MBMS gateway, and the MBMS session control module 2208 may be configured to initiate an MBMS session with the BM-SC. In this configuration, the apparatus may have an M1 interface with an MBMS gateway and an M2 interface with an MCE.

In another configuration, the reception module 2204 may be configured to receive information from an HMS, in which the MBSFN subframes of the first base station are determined based on the information received from the HMS. The information from the HMS may indicate an MBSFN configuration. The transmission module 2210 may be configured to transmit, based on the MBSFN configuration, at least one of a SIB 13, an MCCH change notification, an MCCH synchronously with the first base station at the frequency, or an MTCH synchronously with the first base station at the frequency.

In another configuration, the reception module 2204 may be configured to receive a SIB 2 from the first base station, in which the MBSFN subframes are determined based on the received SIB 2. In another configuration, the reception module 2204 may be configured to receive MSI, in which the MBSFN subframes are further determined based on the received MSI.

In another configuration, the reception module 2204 may be configured to receive a SIB 13 from the first base station. The MBSFN configuration module 2206 may be configured to obtain an MCCH from the first base station based on the received SIB 13 and obtain an MBSFN configuration based on the obtained MCCH and the SIB 13. The transmission module 2210 may be configured to transmit at least one of a SIB 13, an MCCH change notification, or an MCCH, in which the MCCH is transmitted synchronously with the first base station at the frequency of the first base station.

The apparatus may include additional modules that perform each of the blocks of the algorithm in the aforementioned flow charts of FIGS. 15 and 17. As such, each block in the aforementioned flow charts of FIGS. 15 and 17 may be performed by a module and the apparatus may include one or more of those modules. The modules may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by a processor configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

FIG. 23 is a diagram 2300 illustrating an example of a hardware implementation for an apparatus 2202′ employing a processing system 2314. The processing system 2314 may be implemented with a bus architecture, represented generally by the bus 2324. The bus 2324 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2314 and the overall design constraints. The bus 2324 links together various circuits including one or more processors and/or hardware modules, represented by the processor 2304, the reception module 2204, the MBSFN configuration module 2206, the MBMS session control module 2208, the transmission module 2210, and the computer-readable medium/memory 2306. The bus 2324 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2314 may be coupled to a transceiver 2310. The transceiver 2310 is coupled to one or more antennas 2320. The transceiver 2310 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2310 receives a signal from the one or more antennas 2320, extracts information from the received signal, and provides the extracted information to the processing system 2314, specifically the reception module 2204. In addition, the transceiver 2310 receives information from the processing system 2314, specifically the transmission module 2210, and based on the received information, generates a signal to be applied to the one or more antennas 2320. The processing system 2314 includes a processor 2304 coupled to a computer-readable medium/memory 2306. The processor 2304 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 2306. The software, when executed by the processor 2304, causes the processing system 2314 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 2306 may also be used for storing data that is manipulated by the processor 2304 when executing software. The processing system further includes at least one of the modules 2204, 2206, 2208, and 2210. The modules may be software modules running in the processor 2304, resident/stored in the computer readable medium/memory 2306, one or more hardware modules coupled to the processor 2304, or some combination thereof. The processing system 2314 may be a component of the eNB 610 and may include the memory 676 and/or at least one of the TX processor 616, the RX processor 670, and the controller/processor 675.

In one configuration, the apparatus 2202/2202′ for wireless communication includes means for determining MBSFN subframes at a frequency of a first base station. The first base station has a first power class, and the apparatus 2202/2202′ has a second power class lower than the first power class. The apparatus includes means for determining, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals by the first base station. The apparatus includes means for transmitting, at the frequency, unicast control information in a subset of the first set of symbols. The apparatus includes means for transmitting, at the frequency, unicast data with a reduced power in the second set of symbols. The apparatus may include means for transmitting, at the frequency, a SIB 13 in non-MBSFN subframes and an MCCH change notification in the first set of symbols with a SIB 13 and an MCCH change notification transmitted by the first base station. The apparatus may include means for determining resources within the second set of symbols used by the first base station for transmitting an MCCH. The apparatus may include means for transmitting, synchronously with the first base station at the frequency, the MCCH in the second set of symbols within the determined resources. The apparatus may include means for determining additional resources within the second set of symbols used by the first base station for transmitting an MTCH. The apparatus may include means for transmitting, synchronously with the first base station at the frequency, the MTCH in the second set of symbols within the determined additional resources.

In one configuration, the apparatus may include means for joining an MBMS session associated with a BM-SC. In this configuration, the apparatus may have an M1 interface with an MBMS gateway and an M2 interface with an MCE.

In another configuration, the apparatus may include means for receiving USD bootstrapping information, means for obtaining a USD based on the USD bootstrapping information, and means for obtaining a multicast IP address and a source IP address from the USD. The transmitted SIB 13, MCCH change notification, MCCH, and MTCH may be based on the obtained multicast IP address and the obtained source IP address. In this configuration, the apparatus may have an M1 interface with an MBMS gateway.

In another configuration, the apparatus may include means for sending an MBMS session start initiation to a BM-SC through the MCE, the MME, and the MBMS gateway, and means for initiating an MBMS session with the BM-SC. In this configuration, the apparatus may have an M1 interface with an MBMS gateway and an M2 interface with an MCE.

In another configuration, the apparatus may include means for receiving information from an HMS, in which the MBSFN subframes of the first base station are determined based on the information received from the HMS. In one aspect, the information from the HMS indicates an MBSFN configuration. In this aspect, the apparatus may include means for transmitting, based on the MBSFN configuration, at least one of a SIB 13, an MCCH change notification, an MCCH synchronously with the first base station at the frequency, or an MTCH synchronously with the first base station at the frequency.

In another configuration, the apparatus may include means for receiving a SIB 2 from the first base station, in which the MBSFN subframes are determined based on the received SIB 2. The apparatus may include means for receiving MSI, in which the MBSFN subframes are further determined based on the received MSI.

In another configuration, the apparatus may include means for receiving a SIB 13 from the first base station, means for obtaining an MBSFN configuration based on the received SIB 13, and means for transmitting a SIB 13 and an MCCH change notification based on the MBSFN configuration.

In another configuration, the apparatus may include means for receiving a SIB 13 from the first base station, means for obtaining an MCCH from the first base station based on the received SIB 13, means for obtaining an MBSFN configuration based on the obtained MCCH and the SIB 13, and means for transmitting at least one of a SIB 13, an MCCH change notification, an MCCH based on the MBSFN configuration, and the MCCH may be transmitted synchronously with the first base station at the frequency.

The aforementioned means may be one or more of the aforementioned modules of the apparatus 2202 and/or the processing system 2314 of the apparatus 2202′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system 2314 may include the TX Processor 616, the RX Processor 670, and the controller/processor 675. As such, in one configuration, the aforementioned means may be the TX Processor 616, the RX Processor 670, and the controller/processor 675 configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in the processes/flow charts disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes/flow charts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.” 

What is claimed is:
 1. A method of wireless communication of a second base station, comprising: determining multicast broadcast single frequency network (MBSFN) subframes used by a first base station at a frequency, the first base station having a first power class, the second base station having a second power class lower than the first power class; determining, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals by the first base station; transmitting, at the frequency, unicast control information in a subset of the first set of symbols; and transmitting, at the frequency, unicast data with a reduced power in the second set of symbols.
 2. The method of claim 1, further comprising transmitting, at the frequency, a system information block (SIB) 13 in non-MBSFN subframes and a multicast control channel (MCCH) change notification in the first set of symbols.
 3. The method of claim 2, further comprising: determining resources within the second set of symbols used by the first base station for transmitting a multicast control channel (MCCH); and transmitting, synchronously with the first base station at the frequency, the MCCH in the second set of symbols within the determined resources.
 4. The method of claim 3, further comprising: determining additional resources within the second set of symbols used by the first base station for transmitting a multicast traffic channel (MTCH); and transmitting, synchronously with the first base station at the frequency, the MTCH in the second set of symbols within the determined additional resources.
 5. The method of claim 4, wherein the second base station has an M1 interface with a multimedia broadcast multicast service (MBMS) gateway and an M2 interface with a multicast coordination entity (MCE), the method further comprising joining an MBMS session associated with a broadcast multicast service center (BM-SC).
 6. The method of claim 4, wherein the second base station has an M1 interface with a multimedia broadcast multicast service (MBMS) gateway, the method further comprising: receiving user service description (USD) bootstrapping information; obtaining a USD based on the USD bootstrapping information; and obtaining a multicast Internet Protocol (IP) address and a source IP address from the USD, wherein the SIB 13, the MCCH change notification, the MCCH, and the MTCH are based on the obtained multicast IP address and the obtained source IP address.
 7. The method of claim 4, wherein the second base station has an M1 interface with a multimedia broadcast multicast service (MBMS) gateway and an M2 interface with a multicast coordination entity (MCE), the method further comprising: sending an MBMS session start initiation to a broadcast multicast service center (BM-SC) through the MCE, a mobility management entity (MME), and the MBMS gateway to initiate an MBMS session with the BM-SC.
 8. The method of claim 1, further comprising receiving information from a home evolved node B (eNB) (HeNB) management system (HMS), wherein the MBSFN subframes of the first base station are determined based on the information received from the HMS.
 9. The method of claim 8, wherein the information from the HMS indicates an MBSFN configuration, and the method further comprises transmitting, based on the MBSFN configuration, at least one of a system information block (SIB) 13, a multicast control channel (MCCH) change notification, an MCCH synchronously with the first base station at the frequency, or a multicast traffic channel (MTCH) synchronously with the first base station at the frequency.
 10. The method of claim 1, further comprising receiving a system information block (SIB) 2 from the first base station, wherein the MBSFN subframes are determined based on the received SIB
 2. 11. The method of claim 1, further comprising: receiving a system information block (SIB) 13 from the first base station; obtaining an MBSFN configuration based on the received SIB 13; and transmitting, at the frequency, the SIB 13 and a multicast control channel (MCCH) change notification based on the MBSFN configuration.
 12. The method of claim 1, further comprising receiving multicast channel (MCH) scheduling information (MSI), wherein the MBSFN subframes are further determined based on the received MSI.
 13. The method of claim 12, further comprising: receiving a system information block (SIB) 13 from the first base station; obtaining a multicast control channel (MCCH) from the first base station based on the received SIB 13; obtaining an MBSFN configuration based on the obtained MCCH and the SIB 13; and transmitting, at the frequency, the SIB 13, an MCCH change notification, and the MCCH based on the MBSFN configuration, wherein the MCCH is transmitted synchronously with the first base station at the frequency.
 14. An apparatus of wireless communication comprising: means for determining multicast broadcast single frequency network (MBSFN) subframes used by a first base station at a frequency, the first base station having a first power class, the apparatus having a second power class lower than the first power class; means for determining, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals by the first base station; means for transmitting, at the frequency, unicast control information in a subset of the first set of symbols; and means for transmitting, at the frequency, unicast data with a reduced power in the second set of symbols.
 15. The apparatus of claim 14, further comprising means for transmitting, at the frequency, a system information block (SIB) 13 in non-MBSFN subframes and a multicast control channel (MCCH) change notification in the first set of symbols.
 16. The apparatus of claim 15, further comprising: means for determining resources within the second set of symbols used by the first base station for transmitting a multicast control channel (MCCH); and means for transmitting, synchronously with the first base station at the frequency, the MCCH in the second set of symbols within the determined resources.
 17. An apparatus for wireless communication, comprising: a memory; and at least one processor coupled to the memory and configured to: determine multicast broadcast single frequency network (MBSFN) subframes used by a first base station at a frequency, the first base station having a first power class, the apparatus having a second power class lower than the first power class; determine, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals by the first base station; transmit, at the frequency, unicast control information in a subset of the first set of symbols; and transmit, at the frequency, unicast data with a reduced power in the second set of symbols.
 18. The apparatus of claim 17, wherein the at least one processor is further configured to transmit, at the frequency, a system information block (SIB) 13 in non-MBSFN subframes and a multicast control channel (MCCH) change notification in the first set of symbols.
 19. The apparatus of claim 18, wherein the at least one processor is further configured to: determine resources within the second set of symbols used by the first base station for transmitting a multicast control channel (MCCH); and transmit, synchronously with the first base station at the frequency, the MCCH in the second set of symbols within the determined resources.
 20. The apparatus of claim 19, wherein the at least one processor is further configured to: determine additional resources within the second set of symbols used by the first base station for transmitting a multicast traffic channel (MTCH); and transmit, synchronously with the first base station at the frequency, the MTCH in the second set of symbols within the determined additional resources.
 21. The apparatus of claim 20, wherein the apparatus has an M1 interface with a multimedia broadcast multicast service (MBMS) gateway and an M2 interface with a multicast coordination entity (MCE), and wherein the at least one processor is further configured to join an MBMS session associated with a broadcast multicast service center (BM-SC).
 22. The apparatus of claim 20, wherein the apparatus has an M1 interface with a multimedia broadcast multicast service (MBMS) gateway, and wherein the at least one processor is further configured to: receive user service description (USD) bootstrapping information; obtain a USD based on the USD bootstrapping information; and obtain a multicast Internet Protocol (IP) address and a source IP address from the USD, wherein the SIB 13, the MCCH change notification, the MCCH, and the MTCH are based on the obtained multicast IP address and the obtained source IP address.
 23. The apparatus of claim 20, wherein the apparatus has an M1 interface with a multimedia broadcast multicast service (MBMS) gateway and an M2 interface with a multicast coordination entity (MCE), and wherein the at least one processor is further configured to: send an MBMS session start initiation to a broadcast multicast service center (BM-SC) through the MCE, a mobility management entity (MME), and the MBMS gateway to initiate an MBMS session with the BM-SC.
 24. The apparatus of claim 17, wherein the at least one processor is further configured to receive information from a home evolved node B (eNB) (HeNB) management system (HMS), wherein the MBSFN subframes of the first base station are determined based on the information received from the HMS.
 25. The apparatus of claim 24, wherein the information from the HMS indicates an MBSFN configuration, and wherein the at least one processor is further configured to transmit, based on the MBSFN configuration, at least one of a system information block (SIB) 13, a multicast control channel (MCCH) change notification, an MCCH synchronously with the first base station at the frequency, or a multicast traffic channel (MTCH) synchronously with the first base station at the frequency.
 26. The apparatus of claim 17, wherein the at least one processor is further configured to receive a system information block (SIB) 2 from the first base station, wherein the MBSFN subframes are determined based on the received SIB
 2. 27. The apparatus of claim 17, wherein the at least one processor is further configured to: receive a system information block (SIB) 13 from the first base station; obtain an MBSFN configuration based on the received SIB 13; and transmit, at the frequency, the SIB 13 and a multicast control channel (MCCH) change notification based on the MBSFN configuration.
 28. The apparatus of claim 17, wherein the at least one processor is further configured to receive multicast channel (MCH) scheduling information (MSI), wherein the MBSFN subframes are further determined based on the received MSI.
 29. The apparatus of claim 28, wherein the at least one processor is further configured to: receive a system information block (SIB) 13 from the first base station; obtain a multicast control channel (MCCH) from the first base station based on the received SIB 13; obtain an MBSFN configuration based on the obtained MCCH and the SIB 13; and transmit, at the frequency, the SIB 13, an MCCH change notification, and the MCCH based on the MBSFN configuration, wherein the MCCH is transmitted synchronously with the first base station at the frequency.
 30. A computer-readable medium, associated with a second base station and storing computer executable code for wireless communication, comprising code for: determining multicast broadcast single frequency network (MBSFN) subframes used by a first base station at a frequency, the first base station having a first power class, the second base station having a second power class lower than the first power class; determining, in the MBSFN subframes, a first set of symbols used for control information by the first base station and a second set of symbols used for MBSFN signals by the first base station; transmitting, at the frequency, unicast control information in a subset of the first set of symbols; and transmitting, at the frequency, unicast data with a reduced power in the second set of symbols. 